Valve-gear for fluid-pressure engines.



A. G. MUMFORD & A. ANTHONY. VALVE GEAR FOR FLUID PRESSURE ENGINES.APPLICATION FILED APR. 29, 1912.

1,056,1 15. Patented Mar. 18, 1913.

FIG. I.

WITNESSES INVENTORS (LTPW flaMumford. y Ann/thong Attorney COLUMBIAPLANOGRAPH co., WASHINGTON. 0 c4 UNITED STATES PATENT OFFICE- ARTHUR G.MUMFORI) AND ALFRED ANTHONY, OF OOLGI-IESTER, EN GLAND.

VALVE-GEAR FOR- FLUID-PRESSURE ENGINES.

To aZZ whom it may concern:

Be itknown that we, ARTHUR GEORGE ltlrmrono and ALFRED Axrrroxy,subjects of the King of Great Britain and Ireland, and respectivelyresiding at The Culver Street Engineering IVorks, Oolchester, in thecounty of Essex, England, and Beaconsfield avenue, Colcheste-r, in thecounty of Essex, England, have invented certain new and usefulImprovements in Valve-Gear for Steam and other Fluid Pressure Engines,of which the following is a specification, reference being had thereinto the accompanying drawing.

This invention relates to the valve gear of fluid pressure engines ofthe direct-action type, 27. c. the type in which the reciprocatingaction of the piston is imparted direct to the purpose for which thepower is required without the intervention of a crank or its equivalent,and it relates particularly to that type of direct-action engine inwhich the main distributing slide valve is operated by a shuttle pistonvalve which receives its motion partly from the piston rod of the engineand partly from the pressure of the fluid employed to drive the engine.

In valve gears of the type specified the exhaust ports which put theends of the shuttle valve cylinder into communication with the mainexhaust are controlled by the shuttle valve, and consequently during alarge portion of that part of the travel of said valve, which iseffected by the piston rod of the engine, said valve is moving againstthe full pressure of the steam.

The object of the present invention is to balance this pressure so as tominimize the force required to move the shuttle valve during thatportion of its travel when it is receiving motion from the piston rod ofthe engine, whereby greater smoothness of working is attained and thedurability of the working parts is materially enhanceda Ive attain thisend by controlling the exhaust ports of the shuttle valve cylinder bothby the shuttle valve and by the slide valve, so that communicationbetween the ends of said valve cylinder and the main exhaust is onlyestablished at that end toward which the shuttle valve is traveling,that is.

to say, when it is required to effect the reversal of the valve by fluidpressure.

In the accompanying drawing which illustrates this invention :-Figure lis a Specification of Letters Patent.

Application filed April 29, 1912.

Patented Mar. 18, 1913.

Serial No. 693,856.

broken view in longitudinal section of the improved valve gear adaptedfor a steam engine, Fig. 2 is a view in plan, and Fig. 3 is a view intransverse section on lines a" a: Fig. 2.

Throughout the views similar parts are marked with like letters ofreference.

The shuttle valve 64, which is of the usual construction, is mounted ina cylinder Z) which is preferably made in one with the steam chest 0.The slide valve (Z, which controls the main admission ports 6 c and themain exhaust port f, is operated by the shuttle valve (4 by means of astrap piece 9 carried by said shuttle valve which alternately engagesfirst one end and then the other end of a recess 61 in the back face ofthe slide valve so as to permit of a certain amount of lost motionbetween the valves. The shuttle valve a is operated by a rod h whichreceives a positive motion from the piston rod 01' other reciprocatingpart of the engine through any suitable mechanism. This Valve rod h isnot fixed to the valve (4 but passes freely into it and carries a collar71 at its back end which works in a recess a at the back end of thevalve so that the valve has a limited amountof free movement relative tothe rod.

In the ends of the shuttle valve a are small L-shaped ports Z and Zwhich put the ends 6 and b of the valve cylinder alternately intocommunication with the steam chest 0 and with the exhaust ports m and mThese exhaust ports instead of communicating directly with the mainexhaust port 7 are connected by passages m" with ports m and m locatedin the face of the seating (Z of the slide valve (Z on either side ofthe ports a and f. In the slide valve (Z are two ports 0 and 0 which runbetween the face of the slide valve (Z and the exhaust cavity 6Zthereof. These ports are so arranged that at predetermined periodsduring the travel of the slide valve in either direction they place theports m and m in communication with the main exhaust port f through theexhaust cavity (Z of the valve.

The action of the valve gear is as follows :-Assuming the two valves aand (Z to be in the position shown in Fig. 1, the forward end 6 of thevalve cylinder is in communication with the steam chest 0 by the port Zso that the pressure in said end of cylinder is the same as that in thesteam chest 0 and the other end. 6 of the valve (When the 'alve he valve(Z, has moved in the toe :i1'l0\v'-1l1l(l8l the influence ol the l'flllfle-so l'ar that the port Z registers with the port m, the port 7212registers with the passage 0, and the port 5 opens to the steam chest.1; the steam pressure in the back end oil the valve cylinder causes theshuttle valve to contii'iue its :liorward motion which in not opposed bythe pressure o'l'f he steam in the front end o t the 'alve cylinder asthe trout end. 7f of said cylinder open to the i rain exhaust port j bythe ports Z, m, m" and o, and by the exhaust cavity (Z of the. va ve d.llurtl'icr movement of the two 'alves (i and (Z in the direction of thearrow ta the port 0 out of i ister with the port w thereby shutting oilthe main exhaust poi-t from the front end. Z) of the valve cylinder, andso causes the valve to come to rest. "the slide valve (Z having nowopened the rear admission port c, the valve rod h commences to more in.the opposite direction to the arrow and in due time its enlarged end 72,contacts the other end of the recess a and causes the shuttle valve o tomove with i s the port Z open to the steam chest 0 lo stea 1 pressure inthe back end 6 of the cvlinder opposed to the movement of u ttle v lve,but as the front end 6 of i v cylinder is notopen to the main st f,

by reason of the ports a and 0 not registering, the pressure of thefluid. in

iacl; endi Zf oi the valve cylinder is bal- 3y the pressure oi the steamleaking i-astthe forward end of the valve into the forward end 0 of thevalve cylinder. l ur- 'tliEl' movement of the 'alve a on its returnstroke-which brings the ports m and 0' into register takes the port Zout of register with the passage m so that there is still nocommunication between the front end If of the valve cylinder and themain exhaust port j".

li hat we claim as our invention, and desire to secure by Letters Patenti 1. n a valve gear for steam or other fluid pressure engines, thecombination with a main slide valve controlling the adm sion and er; ustports of the engine, of a cylinder in c nmunication with. the steamchest containing the slide valve, a piston valve 0" the shuttle typeworking in said cylinder, a

coupling between aid valves whereby the 1,oac,115

shuttle valve operates the slide valve with a predeter nined amount oflost motion, means for imparting motion to the shuttle valve with apredetermined amount of lost motion, ports in the ends of the pistonshuttle va ve cylinder leading to the slide valve lace, ports in theends of the piston shuttle valve for establishing connmmieation betweenthe ends of said cylinder and the steam chest and the ports leading fromthe ends of the piston shuttle valve cylinder to the slide valve tacoI'CSPCCtiYQlY, and ports in the slide valve for establishingcommunication between the ports in the slide valve taco and theexhaustcavity of said valve, as set forthv 2. in a valve gear tor steamor other fluid pressure engines, the combination with a main slide valvecontrolling the admission and exhaustports of the engine, of a cylinderin communication with the steam chest containing the slide valve, :1piston valve oi? the shuttle type woriting in said cylinder, :1 couplingbetween said valves whereby the shuttle valve operates the slide valvewith t predetermined amount of lost motion, means for imparting motionto the shuttle valve with a predetermine l amount of lost motion, anexhaust port in each end ot the piston shuttle valve eyiinder-said portsleading to the slide valve face and opening thereto on either side ofthe main admission and e:'- haust ports of the engine, ports in the endsot the piston shuttle "alv-e for establishing comi'nunication betweenthe ends of the piston shuttle valve cylinder and the steam chest andthe exhaust ports of the shuttle valve cylinder respectively, and portsn the slide valve for establishi communieation betw-en the exhaust portsin. the slide valve face and the exhaust cavity of said valve, as setforth.

3. li a device of the character described, the con'ibination of a slidevalve, a steamchest containing said slide-valve, a piston *alve oi? theshuttlelyme, a coupling; between said. valves, said coupling having," asliding connection with said slide valve and a Fixed connection withsaid piston-valve, and a piston rod having a sliding); connection withsaid piston-valve, said piston valve and said slidevalve having;- portsalternately establishing commimication through the steam chest portsvith the respective ends oft the pistonwalve chamber, and the exhaustchamber of the slide-valve.

4;. In a device of the character descril'ied, the combination of aSllClY llVQ, a steamchest containing said slid-ovalve, a piston valve 0;the shuttle-type, having a chainbered end, a piston rod received by saidpiston-valve, and having a headed end received within said chambered endof the pistonvalve, and a coupling between said slidevalve and saidpiston-valve said coupling having JIQCl connection with Said pistonnames in the presence of subscribing Witnesses.

A. G. MUMFORD. A. ANTHONY.

\Vitnesses:

A. H. \VYATT, F. NOBLE.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents Washington, I). C.

